An Ohio federal judge on Monday will consider a request for a preliminary injunction to stop the Zales jewelry chain from claiming its Celebration Fire stones are the “most brilliant diamonds in the world.”

The suit was filed against the Zale Corp. by Sterling Jewelers Inc., a unit of a company that also owns Kay Jewelers and Jared the Galleria of Jewelry, report the Wall Street Journal (sub. req.) and the Dallas Morning News Biz Beat Blog.

“Zale’s claim that it has proven its Fire diamonds to be more brilliant than any other cut of diamonds in the world can be true only if its Fire diamonds have been tested against every other cut diamond in the world,” the suit says. “Zale’s admission that it has tested only a ‘select’ subset of round-cut diamonds renders this claim false.”

Zale Corp. spokeswoman Roxane Berry told the newspaper that its advertising is based on findings by an independent laboratory, and the ads make that clear. Zale asserts that Sterling’s own expert tested a randomly selected Celebration Fire diamond and gave it higher scores for brilliance that than 97.2 percent of other diamonds tested.

According to the Wall Street Journal, the industry is “rife with superlatives designed to tug at consumers’ emotions.” The Leo Diamond, made by Leo Schacter Diamonds and sold at Kay and Jared, is touted as “the first diamond ever to be certified visibly brighter.” Another diamond brand, Hearts on Fire, is called “the world’s most perfectly cut diamond.”